1. Field of the Invention
The present invention relates generally to an optical probe assembly and, more particularly, to an optical system exhibiting multiple focal lengths.
2. Discussion of the Prior Art
Video probe assemblies include borescopes, videoscopes, fiberscopes, endoscopes, etc. Video probe assemblies are types of non-destructive evaluation tools that can inspect inaccessible and/or hard to reach environments for targets such as defects, wear and tear, inclusions, deformations, cracks, openings, etc. When a target is illuminated within the environment, an image of the target can be formed with an optical system housed within the video probe assembly.
In past examples, the optical system of existing probes were capable of only relatively small focal length changes. This relatively small focal length change made it difficult for the video probe assembly to inspect a large range of field, as the targets (e.g., defects, wear and tear, inclusions, cracks, openings, etc.) were frequently out of focus. Further, movement of the probe assembly to improve focus was relatively limited due to size constraints within the environment. Accordingly, it would be beneficial to provide an optical system that exhibits a larger range of focal length changes to improve focus and zooming functionalities.